The fan pictured below is from Cox/Estes (phone: 1.800.451.0339). The unit
without the motor weighs 0.32 oz (9.1g). The total weight with the motor
is 1.1 oz (31.8g). The inner diameter of the duct is 1.875 in (4.76cm).

Cox/Estes prototype small ducted fan.

Cox sent me the images below of the fan inside a foam nacelle that they
sell with the unit. The fan and foam nacelle together weigh 1.47 oz
(41.6g).

Cox fan with foam nacelle.

Here are Cox's performance characteristics with the nacelle and
characteristics from my testing without the nacelle:

Here is a fan from Knight & Pridham. This is another of the smaller
electric ducted fans (EDF) currently on the market. The total weight of
the unit with the motor is 1.2 oz (35.1g). The inner diameter of the duct
is 1.73 in (4.4cm).

Blue Flame Blaster
Below is a picture of Hi-Line's Blue Flame Blaster EDF. The unit
comes assembled with the motor permanently fitted to the fan. (Maybe
not permanent, but there wouldn't be much left of the fan if you
decided to take the motor out of it.) The unit weighs 2.7 oz (76.4g),
and the inner diameter of the duct is 2.5 in (6.35cm).

Hi-Line's Blue Flame Blaster.

Here are some of the Blue Flame Blaster's characteristics from
my experimenting: